import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
public class ReetlockABC { public static void main(String[] args) {
// TODO Auto-generated method stub
final Out out = new Out();
new Thread(new Runnable() {@Override
public void run() {
// TODO Auto-generated method stub
try {
out.pB();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}).start();
new Thread(new Runnable() {@Override
public void run() {
// TODO Auto-generated method stub
try {
out.pA();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}).start();
new Thread(new Runnable() {@Override
public void run() {
// TODO Auto-generated method stub
try {
out.pC();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}).start();
}}class Out {
Lock lock = new ReentrantLock();
Condition a_b = lock.newCondition();
//可以理解为等待a唤醒b
Condition b_c = lock.newCondition();
Condition c_a = lock.newCondition();
int flag = 1;
public void pA() throws InterruptedException {
while (true) {
lock.lock();
while (flag != 1)
c_a.await();
System.out.println("a");
flag = 2;
a_b.signal();
lock.unlock();
}
} public void pB() throws InterruptedException {
while (true) {
lock.lock();
while (flag != 2)
a_b.await();
System.out.println("b");
flag = 3;
b_c.signal();
lock.unlock();
}
} public void pC() throws InterruptedException {
while (true) {
lock.lock();
while (flag != 3)
b_c.await();
System.out.println("c");
flag = 1;
c_a.signal();
lock.unlock();
}
}
}
以前我用synchronized同步块时，当有三个或以上的线程时必须用obj.signalAll(); （obj.signal()可能会唤醒错人导致死锁或者用嵌套的synchronized(麻烦死了而且容易死锁))，用lock的Condition可以唤醒指定对象，不用唤醒全部
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